Fabrics, of course, are and have been used as coverings for a large variety of articles. Because of the flexibility of fabric materials, they are frequently adhered, for example, by adhesive, to an underlying rigid substrate, such as wood or plasterboard, which affords rigidity to the fabric. The ease of manufacture of fabrics in many different colors, textures, patterns and raw materials lends their use in a wide variety of applications. The flexible nature of fabrics, however, frequently is a detriment to their application and end use. This will become apparent from the following discussion of the use of fabrics in window treatments and coverings, for example, wall panels, representative of the ofttimes desirable but sometimes disadvantageous flexibility of the fabrics.
Window treatments are conventionally categorized as soft and hard treatments. For example, soft window treatments might include draperies, curtains and the like for windows or walls where the fabric forming the draperies or curtains is typically decorative and highly flexible. That is, they do not have a stiffness attributable to the fabric per se such that the fabric may have a self-supporting shape. Hard window treatments, on the other hand, may include blinds, both vertical and horizontal, including mini-blinds as well as pleated shades. The vertical blind segment of the window treatment market has grown rapidly, much to the detriment of the soft window treatment market. That is to say, the materials normally employed in the hard window treatment market from which vertical and horizontal blinds are made, for example, might comprise relatively inflexible plastic material, such as PVC, or aluminum, shaped to have a degree of stiffness or rigidity. Very little of the hard window treatment market includes fabric materials, although certain vertical blinds have previously been formed of treated, non-woven, as well as woven, fabrics. For example, there has been previously provided a stitch-through drapery fabric which may have various surface effects, ranging from casements to textures and which has been treated with resins or a polymer to achieve a stiff, self-supporting slat for vertical blinds. However, the treatment is a separate step, not part of the fabric formation and is thus limited to the addition of further materials to the fabric beyond those necessary to make it.
Also, there has been increasingly a demand for hard window treatments having a more elegant drapery look. Such fabrics have to be finished in such a way that they have sufficient stiffness to make them suitable for such window coverings. The finishing processes required for this purpose are difficult, lengthy and expensive. The physical properties of the resulting fabrics are not always satisfactory because high humidity and heat, as typically occurs at a window, cause a variation from the predetermined finished shape. For example, vertical slats or vanes formed of finished fabric materials will sometimes cup-in, i.e., form a non-controllable convex or concave surface, rather than retain a flat surface configuration, as desired. Alternately, original cup-shaped slats may become flat or obtain other shapes upon application of heat and/or humidity. Loss of definition has been found to be especially true with woven fabrics made mostly with rayon wefts.
Fabric coverings for wall panels is another example of the undesirable flexibility of fabric for certain applications, although other attributes of fabrics, such as ready and inexpensive manufacture, wide variations in color, patterns, texture, etc., make their use highly desirable as wall panels. For example, fabric coated wallpaper is relatively difficult to apply to a wall due in no small part to the flexibility of the fabric itself. Usually, a professional wallpaper hanger is required. Flexible fabrics are also difficult to cut to the required size and shape. Consequently, the oftentimes highly desirable characteristic of flexibility is frequently detrimental to the use of fabrics in certain applications. Thus, there has developed a need for a stiff fabric which obtains and retains during use a predetermined stiffness but which does not require further treatments such as the application of additional materials to the fabric to obtain and retain the stiffness.
In prior application Ser. No. 111,521, filed Aug. 25, 1993, now U. S. Pat. No. 5,436,064 there is disclosed a stiff fabric composite formed of a non-woven or woven fabric having a substrate comprised of synthetic fibers or blends of fibers rendering the substrate thermally formable or thermobondable to impart stiffness to the resulting fabric. Such stiff fabric composites retain the appearance of, and resemblance to, woven fabrics yet have stiffness characteristics rendering them useful in the applications noted above. These composites, however, require, apart from the cost of the two materials themselves, additional treatments. For example, needlepunching the substrate to the fabric and carefully controlled heat treatment of the composite material increase the costs of providing such stiff fabric composite. While the stiff fabric composite of that invention is eminently suitable for the above-noted applications, there is also a need for a reduced cost stiff fabric suitable for those purposes and which would have a mass marketing appeal.